Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for HD 189733: 12-22 (23), 12-23 (22), 12-24 (20), 12-25 (19), 12-26 (18) — by astronomy; check the weather when the night is within four days.

2038-12-22astronomy score per night — click a bar for that night2039-01-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-12-22 Wed	23	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:20	11.51	14%	80.6°
2038-12-23 Thu	22	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.51	6%	70.5°
2038-12-24 Fri	20	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	2%	61.2°
2038-12-25 Sat	19	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:05	11.5	0%	53.3°
2038-12-26 Sun	18	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	1%	47.8°
2038-12-27 Mon	16	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	5%	45.3°
2038-12-28 Tue	13	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.48	11%	46.3°
2038-12-29 Wed	11	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:50	11.48	18%	50.1°
2038-12-30 Thu	8	—	unknown	18:10–19:20 (marginal, 1.17 h)	71.1° 13:45	11.47	27%	56.0°
2038-12-31 Fri	6	—	unknown	18:45–19:15 (marginal, 0.5 h)	71.1° 13:45	11.46	37%	63.2°
2039-01-01 Sat	5	—	unknown	18:45–19:15 (marginal, 0.5 h)	71.1° 13:40	11.45	46%	71.0°
2039-01-02 Sun	4	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.44	56%	79.1°
2039-01-03 Mon	3	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.43	65%	87.4°
2039-01-04 Tue	3	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:30	11.42	74%	95.8°
2039-01-05 Wed	2	—	unknown	18:45–18:55 (marginal, 0.17 h)	71.1° 13:25	11.4	82%	104.0°
2039-01-06 Thu	2	—	unknown	18:50–18:55 (marginal, 0.08 h)	71.1° 13:20	11.39	88%	111.9°
2039-01-07 Fri	1	—	unknown	—	71.1° 13:15	11.38	94%	119.3°
2039-01-08 Sat	1	—	unknown	—	71.1° 13:10	11.36	98%	125.8°
2039-01-09 Sun	1	—	unknown	—	71.1° 13:10	11.34	100%	131.0°
2039-01-10 Mon	1	—	unknown	—	71.1° 13:05	11.33	100%	134.1°
2039-01-11 Tue	1	—	unknown	—	71.1° 13:00	11.31	98%	134.6°
2039-01-12 Wed	1	—	unknown	—	71.1° 12:55	11.29	94%	132.3°
2039-01-13 Thu	0	—	unknown	—	71.1° 12:50	11.27	88%	127.5°
2039-01-14 Fri	0	—	unknown	—	71.1° 12:50	11.25	80%	120.7°
2039-01-15 Sat	0	—	unknown	—	71.1° 12:45	11.23	70%	112.4°
2039-01-16 Sun	0	—	unknown	—	71.1° 12:40	11.21	59%	103.3°
2039-01-17 Mon	0	—	unknown	—	71.1° 12:35	11.18	48%	93.6°
2039-01-18 Tue	0	—	unknown	—	71.1° 12:35	11.16	37%	83.6°
2039-01-19 Wed	0	—	unknown	—	71.1° 12:30	11.14	26%	73.8°
2039-01-20 Thu	0	—	unknown	—	71.1° 12:25	11.11	17%	64.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-12-22&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.